A support device is described below for a magnetron arrangement with a rotating target, which has limited susceptibility to damage during operation with medium frequency current, i.e., in the range from a few hundred hertz to about 50 kilohertz.
Magnetron arrangements with a rotating target are known in vacuum coating technology in which a generally tubular target encloses a magnet arrangement, the tubular target being mounted rotatable and drivable so that the target material is uniformly ablated. The tubular target is ordinarily fastened in the vacuum chamber of a vacuum coating installation between two end blocks, which are designed so that they each permit rotatable mounting of the tubular target. Different functions are generally assigned to the two end blocks. One of the end blocks is ordinarily designed as a supply end block to supply the magnetron with cooling water and electrical power and the other end block as a drive end block to introduce a torque to generate rotation of the tubular target.
Known drive end blocks have an electromechanical drive device for this purpose in the form of an electric motor with transmission, which introduces the torque, for example, via bevel gears, spur gears, or cogged belts. This drive apparatus must be potential-free and therefore installed insulated relative to the target and generally also relative to the vacuum chamber. In known drive end blocks the drive device is therefore installed using insulators in the drive end block so that the electric motor is usually situated outside the vacuum chamber on the atmosphere side and a transmission or parts of a transmission or other torque transfer devices, like belt drives and the like, are arranged within the drive end block. Depending on the level of the electrical process voltage, the cost for potential separation can be very high in order to reliably achieve a situation in which the process voltage lying on the tubular target does not arc over to the drive device or vacuum chamber. An example of such an end block is known from patent application EP 1 365 436 A2.
On the other hand, a drive end block for a magnetron arrangement with a rotating target is known from DE 10 2008 033 904, which has an end block housing with a rotatably mounted drive shaft arranged in the end block housing, which is designed on its end accessible from outside of the end block housing for connection to the rotating target and which is designed on its end lying within the end block housing to introduce a torque, and includes an electric motor with a stator and a rotor for generation of a torque, the electric motor being arranged within the end block housing. According to one embodiment it can be prescribed that the electric motor is arranged coaxial to the drive shaft or/and that the torque is directly transferred to the drive shaft.
Starting from the described prior art, an improved support device is to be provided, which has low susceptibility to damage when operated with medium frequency current. End blocks, especially drive end blocks of the type described above, i.e., devices that are arranged in the interior of the vacuum chamber, but also differently configured support devices that are arranged outside the vacuum chamber on the atmosphere side are to be understood under the term support device.